Vitamin D deficiency was highly prevalent among patients newly diagnosed with advanced pancreatic cancer, and black patients had statistically significantly lower levels than white patients, according to a recent study reported by Katherine Van Loon, MD, MPH, of the UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, and colleagues in the Journal of the National Cancer Institute. However, baseline levels among a cohort of patients receiving gemcitabine-based chemotherapy were not associated with progression-free survival or overall survival.
Patients were enrolled in Cancer and Leukemia Group G (CALGB) 80303, a randomized trial finding no difference in overall survival among patients with advanced pancreatic cancer treated with gemcitabine plus placebo (5.9 months) vs gemcitabine plus bevacizumab (Avastin) (5.8 months).
Among a total of 602 patients enrolled in that study, investigators obtained baseline serum 25-hydroxyvitamin D (25[OH]D) measurements for 256 and found that 44.5% were vitamin D deficient (< 20 ng/mL), and 32.4% were insufficient (≥ 20 and < 30 ng/mL). Vitamin D levels were lower in black vs white patients and patients of other/undisclosed race (10.7 vs 22.4 vs 20.9ng/mL, P < .001). Baseline Vitamind D levels were not associated with progression-free survival (hazard ratio [HR] = 1.00, 95% confidence interval [CI] = 0.99–1.01, P = .60) or overall survival (HR = 1.00, 95% CI = 0.99–1.01, P = .95).
The authors commented:
The apparent propensity toward extreme deficiency in patients with advanced pancreatic cancer may reflect malabsorption of this fat-soluble vitamin in those with pancreatic exocrine insufficiency. However, vitamin D concentration is primarily dependent on endogenous production by skin following exposure to ultraviolet rays and, to a lesser extent, on dietary consumption of vitamin D. The greater prevalence of vitamin D deficiency among black patients in our cohort is consistent with other studies and likely due to reduced vitamin D photosynthesis in pigmented skin because of greater melanin content and increased absorption of UVB radiation. Between 2006 and 2010, black Americans had an age-adjusted incidence rate of pancreatic cancer that was 31% higher than in white Americans and an age-adjusted mortality rate that was 27% higher. ■
Van Loon K, et al: J Natl Cancer Inst 106(8):dju185, 2014.